>> yes, sir. >> larry: west virginia has a prominent football team. major problem in nfl and college football and one of the great baseball stars sat out almost the whole year. what is a concussion and what causes it? >> concussion is either the head gets hit or the head gets moved back and forth violently that the brain moves inside the skull. our brain floats in this bath of fluid. cerebral spinal fluid. i think that causes a tearing of fibers, rotation of the brain causes tearing of the fibers so the brain is injured. most of the time it recovers. we think in selected cases we're also finding perhaps a genetic predisposition, in selective cases it can accrue and lead to long-term problems in a minority of players. >> larry: could a problem be in the helmet? >> well, the helmets have undergone a lot of changes and improvements and helmet design is important but in my opinion helmets aren't the whole answer. we need to take the motion of the brain inside the skull out of the game. >> larry: in the nfl they fear it may shorten life. can it? >> well, y